Also known as: severe mental disease · severe mental defect · mental disease or defect
Written by attorneys · grounded in primary & secondary sources — see below
A serious psychotic or comparable impairment that substantially undermines a defendant's capacity to appreciate the wrongfulness of conduct or to conform conduct to law. The condition must be more than a non-psychotic personality disorder, neurosis, or voluntary intoxication. It supplies the qualifying basis for an insanity defense or related mitigation under prevailing standards.
Stephen Shaw, diagnosed with schizophrenia, bypasses security and uploads confidential files because a fixed delusion convinces him that only public exposure will stop a secret cabal. Without the delusion generated by his condition, Shaw would not have committed the access offense. The court therefore acquits him because the charged conduct was the product of his mental disease.
Sabrina Shah is convicted of capital murder. At the penalty phase she offers psychiatric testimony that her severe bipolar disorder produced a manic episode that substantially impaired her capacity to appreciate the wrongfulness of her conduct. The court admits the evidence because it is relevant to whether she should receive imprisonment rather than death.
Select any source to read its text and confirm it supports the definition.
Sofia Stern is acquitted of arson on the ground that her severe schizoaffective disorder excluded responsibility. The court immediately orders her committed to the custody of the Commissioner of Mental Hygiene for placement in an appropriate institution for custody, care, and treatment.
Simon Stern, suffering from a long-documented psychotic disorder, sets fire to a building because a fixed delusion tells him the structure is transmitting surveillance data to federal agents. The court acquits him because the unlawful act was the product of his mental disease or defect.
Solomon Silver is convicted of murder. At sentencing he presents evidence that his severe mental disease impaired his capacity to appreciate the criminality of his conduct or to conform his conduct to law. The sentencer may consider that impairment as a factor supporting a sentence of imprisonment rather than death.
Sierra Santos is charged with first-degree murder. She seeks to introduce expert testimony that her documented mental disease prevented her from forming the required mens rea. The court limits the testimony to whether the disease affected her capacity to appreciate wrongfulness, consistent with the jurisdiction's rules governing mental-disease evidence.
The term requires a serious psychotic or comparable impairment that substantially affects cognitive or volitional capacity. Non-psychotic personality disorders, neuroses, antisocial tendencies, and voluntary intoxication do not qualify even if they impair appreciation of wrongfulness.
Under the Durham rule a defendant receives an acquittal if the charged offense would not have occurred but for the mental disease or defect. The condition must be the originating source of the criminal conduct rather than a concurrent or post-hoc factor.
Yes. When a sentencer may choose between death and imprisonment, evidence that mental disease or defect impaired the defendant's capacity to appreciate wrongfulness or conform conduct to law is admissible in favor of a sentence of imprisonment.
The court must order the defendant committed to the custody of the appropriate mental-health authority for placement in an institution for custody, care, and treatment. Release is possible only upon a later judicial finding that the person may be discharged without danger to self or others.
…the criminality [wrongfulness] of his conduct or to conform his conduct to the requirements of law was impaired as a result of mental disease or defect or intoxication. "(h) The youth of the defendant at the time of the crime." ALI Model Penal Code § 210.6 (Proposed Official Draft 1962). [^maj-45]: As MR. JUSTICE BRENNAN noted in…